The present invention relates to medical treatment apparatus, such as distal protection devices, deployed in a vessel of the body. In one of its more particular aspects this invention relates to the retrieval of such devices. More specifically, the invention relates to a catheter designed for ready retrieval of medical devices.
Any intervention into the human vasculature that uses a guidewire or medical device attached to a guidewire may require back-loading the catheter during the course of the medical procedure. Back loading a guidewire into a catheter from the distal end of the catheter to an exit port positioned proximal from the distal end of the catheter can be difficult without a guiding means. To facilitate back-loading, a guidewire lumen, separate from the catheter main body, may be used. Such a separate lumen can run from proximate the distal end of the catheter to a desired exit location proximate the guidewire entry location.
Medical apparatus, such as distal protection devices, are utilized in both over-the-wire and rapid exchange type catheters. While, typically, there are no unique problems encountered during deployment of such devices, problems can be encountered during device retrieval after an interventional procedure.
During the course of a medical procedure, the need may arise to capture debris, such as grumous matter, emboli, thrombi from the affected vessel. Filters of various types have found use, for example, in trapping blood clots and other debris released into the blood stream. Filters are traps that have been designed to be used to collect dislodged matter such as described above. They serve to provide protection from distal embolization that might result in a major adverse coronary event or other acute complication. Embolization of debris which might be released during such procedures and the resulting sequellae have been described in reports documenting major adverse cardiac event rates. Such events include acute myocardial infarction, revascularization and even death.
In order to address such acute embolic-related complications, distal filtration and protection devices have been developed. Such devices have been designed to work with existing interventional modalities. Such devices provide debris-filtering protection during invasive procedures and are intended to prevent complications of particulate embolization.
Such distal filtration and protection devices are typically deployed at a location along a vessel of the body at a desired location. Such deployment is performed by extending the device outwardly from the distal end of a catheter. In order to facilitate deployment, the device to be deployed typically has components made from a shape-memory or highly elastic material. Consequently, they are able to be collapsed within the catheter and, upon being urged outwardly beyond the distal end of the catheter, they reassume their uncollapsed shape.
Once in place, the protection device performs the function of filtering debris as discussed above. Retrieval of a debris-filled filter offers unique problems.
Since the retrieval of a distal protection device requires a minimum inside diameter to remove the device filled with captured debris, it can be difficult to retrieve a device into a recovery catheter. In order to facilitate back-loading, a separate guidewire lumen may be used. Such a lumen must be configured, however, to be retracted within the catheter main body to afford access to the distal protection device during retrieval. If the lumen does not move, or allow retrieval of the distal protection device into the catheter main body, the captured debris will not be properly retrieved into the distal end of the recovery catheter.
Alternatively, debris may be removed from the distal protection device by means of suction while the distal protection device is still deployed in the vasculature. Suction through the catheter main body could aspirate captured debris from the distal protection device using a syringe or similar device attached to the proximal end of the catheter. Since the main body could be sealed off from the guidewire lumen, pressure losses would not occur resulting in decreased aspiration performance.
No device has yet been developed which is effective to accomplish debris removal in a simple manner.
It is an object of the present invention to provide a catheter in which the removal of debris can be accomplished in a simple, effective manner.
Another object of the invention is to facilitate retrieval of a distal protection device or other medical apparatus.
Another object of the invention is to simplify back-loading a guidewire and device carried by the guidewire into a large inside diameter catheter.
Another object of this invention is to facilitate effective aspiration from a filter deployed in a body vessel.
Other objects and advantages of the present invention will become apparent from the following DETAILED DESCRIPTION OF THE INVENTION.
The catheter of the present invention, in one embodiment, is provided with a collapsible inner lumen which can be used to back-load a guidewire or a device having been deployed on a guidewire. The catheter comprises a catheter main body which is equipped, in that embodiment, with a collapsible inner lumen. The inner lumen is adapted to receive the guidewire. The guidewire may be fed, external of the patient being treated, into the lumen through the distal end of the lumen. The guidewire was previously inserted into the patient mounting a medical device such as a distal protection device. Following its use to capture debris, the protection device is retrieved. Upon retrieval the inner lumen collapses, allowing the filter basket containing debris to be received into the catheter main body.
The collapsible inner lumen can serve as a guidewire conduit extending from the distal end of the catheter main body to a proximal location at the exit port.
It may be appropriate to aspirate through the catheter to remove debris from the filter basket prior to retrieval. Having the inner lumen of the present invention communicating with, and sealed at, the exit port, the present catheter has been found to be an effective way of preventing pressure losses during aspiration, since the lumen is isolated from the interior of the main body of the catheter.
The inner lumen of this embodiment of the catheter of the present invention can be constructed from a variety of thin-walled flexible tubing materials such as thin-walled polytetrafluoroethylene tubing. The thin-walled tubing-to be used as the inner lumen of the present invention should collapse when subjected to a minimal axial force, yet should have sufficient axial strength to prevent kinking during back-loading a guidewire. The minimal axial force for collapsing the inner lumen has been found to fall in the range of about 100 grams to about 500 grams.
The inner lumen can be recessed within the distal end of the catheter main body for about 15-40 cm in the proximal direction in a rapid exchange version. The inner lumen, in this embodiment, is fixed at a proximal end, and can be free floating or attached at the distal end, as desired.
In operation, a distal protection device such as a filter basket is pulled into the distal end of the catheter main body, and the inner lumen collapses under minimal force for retrieval.
In another embodiment of the present invention, the inner lumen is also fixed at a proximal end. As in the first embodiment discussed above, it can be free-floating or attached at its distal end. In this embodiment, however, the lumen does not collapse when subjected to a minimal axial force. Rather, a wall of the lumen is provided with a series of axially extending perforations. When the guidewire is withdrawn to retract, for example, a filter basket, the guidewire xe2x80x9ccutsxe2x80x9d the inner lumen axially along the line of perforation. The guidewire rides up the slit thereby formed, and the filter basket is retracted into the catheter main body passing alongside the inner lumen external with respect thereto.
A further embodiment of the invention includes an inner lumen which is not fixed at its proximal end with respect to the catheter main body. Rather, in this embodiment, the inner lumen is retractable through the exit port, in effect, to withdraw the distal end thereof to recess it within the catheter main body. Such retraction can be accomplished by retracting the guidewire external to the patient being treated.
The present invention is thus an improved catheter for back-loading a device such as a filter having previously been deployed on a guidewire in vasculature of an individual. More specific features and advantages obtained in view of those features will become apparent with reference to the DETAILED DESCRIPTION OF THE INVENTION, appended claims, and accompanying drawing figures.